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Internet exchange points (IXes or IXPs) are common grounds of IP networking, allowing participant Internet service providers (ISPs) to exchange data destined for their respective networks. IXPs are generally located at places with preexisting connections to multiple distinct networks, ''i.e.'',
datacenters
datacenters
, and operate physical infrastructure (
switches In electrical engineering Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems which use electricity, electronics, and electromagnetism. It emerged as an ident ...

switches
) to connect their participants. Organizationally, most IXPs are each independent not-for-profit associations of their constituent participating networks (that is, the set of ISPs which participate at that IXP). The primary alternative to IXPs is private peering, where ISPs directly connect their networks to each other. IXPs reduce the portion of an ISP's traffic that must be delivered via their
upstream Upstream may refer to: * Upstream (bioprocess) * Upstream (film), ''Upstream'' (film), a 1927 film by John Ford * Upstream (mobile marketing), a company * Upstream (networking) * Upstream (newspaper), ''Upstream'' (newspaper), a newspaper covering ...
transit Transit may refer to: Arts and entertainment Film * Transit (1979 film), ''Transit'' (1979 film), a 1979 Israeli film * Transit (2005 film), ''Transit'' (2005 film), a film produced by MTV and Staying-Alive about four people in countries in the wo ...
providers, thereby reducing the average per-bit delivery cost of their service. Furthermore, the increased number of paths available through the IXP improves routing efficiency (by allowing routers to select shorter paths) and
fault-tolerance Fault tolerance is the property that enables a system A system is a group of Interaction, interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its envir ...
. IXPs exhibit the characteristics of the
network effect In economics Economics () is a social science that studies the Production (economics), production, distribution (economics), distribution, and Consumption (economics), consumption of goods and services. Economics focuses on the behavi ...

network effect
.


History

Internet exchange points began as Network Access Points or NAPs, a key component of
Al Gore Albert Arnold Gore Jr. (born March 31, 1948) is an American politician and environmentalist who served as the 45th vice president of the United States from 1993 to 2001. Gore was Bill Clinton's running mate in their Bill Clinton presidential ...

Al Gore
's
National Information Infrastructure The National Information Infrastructure (NII) was the product of the High Performance Computing Act of 1991 The High Performance Computing Act of 1991 (HPCA) is an Act of Congress promulgation, promulgated in the 102nd United States Congress as (Pu ...
(NII) plan, which defined the transition from the US Government-paid-for
NSFNET The National Science Foundation Network (NSFNET) was a program of coordinated, evolving projects sponsored by the National Science Foundation The National Science Foundation (NSF) is an independent agency of the United States government Indep ...
era (when Internet access was government sponsored and commercial traffic was prohibited) to the commercial Internet of today. The four Network Access Points (NAPs) were defined as transitional data communications facilities at which Network Service Providers (NSPs) would exchange traffic, in replacement of the publicly financed
NSFNET The National Science Foundation Network (NSFNET) was a program of coordinated, evolving projects sponsored by the National Science Foundation The National Science Foundation (NSF) is an independent agency of the United States government Indep ...
Internet backbone. The
National Science Foundation The National Science Foundation (NSF) is an independent agency of the United States government Independent or Independents may refer to: Arts, entertainment, and media Artist groups * Independents (artist group)The Independents were a group of ...

National Science Foundation
let contracts supporting the four NAPs, one to MFS Datanet for the preexisting
MAE-East MAE-East was an Internet Exchange Point spread across the east coast of the United States, with locations in Vienna, Virginia; Reston, Virginia; Ashburn, Virginia; New York, New York; and Miami, Florida. It was the eastern branch of the MCI Intern ...
in Washington, D.C., and three others to
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,
Ameritech AT&T Teleholdings, Inc., formerly known as Ameritech Corporation (and before that American Information Technologies Corporation), is an American telecommunication Telecommunication is the transmission of information by various types of tech ...
, and
Pacific Bell The Pacific Bell Telephone Company (Pacific Bell or Pac Bell) is a telephone company that provides telephone service in California. The company is owned by AT&T Inc. through AT&T Teleholdings, and, though separate, is now marketed as “AT&T”. ...

Pacific Bell
, for new facilities of various designs and technologies, in New York (actually
Pennsauken, New Jersey Pennsauken Township is a township A township is a kind of human settlement In geography, statistics and archaeology, a settlement, locality or populated place is a community in which people live. The complexity of a settlement can r ...
), Chicago, and California, respectively. As a transitional strategy, they were effective, providing a bridge from the Internet's beginnings as a government-funded academic experiment, to the modern Internet of many private-sector competitors collaborating to form a network-of-networks, transporting Internet bandwidth from its points-of-production at
Internet Exchange Point Internet exchange points (IXes or IXPs) are common grounds of IP networking, allowing participant Internet service providers (ISPs) to exchange data destined for their respective networks. IXPs are generally located at places with preexisting ...
s to its sites-of-consumption at users' locations. This transition was particularly timely, coming hard on the heels of the ANS CO+RE controversy, which had disturbed the nascent industry, led to congressional hearings, resulted in a law allowing NSF to promote and use networks that carry commercial traffic, prompted a review of the administration of NSFNET by the NSF's Inspector General (no serious problems were found), and caused commercial operators to realize that they needed to be able to communicate with each other independent of third parties or at neutral exchange points. Although the three telco-operated NAPs faded into obscurity relatively quickly after the expiration of the federal subsidies,
MAE-East MAE-East was an Internet Exchange Point spread across the east coast of the United States, with locations in Vienna, Virginia; Reston, Virginia; Ashburn, Virginia; New York, New York; and Miami, Florida. It was the eastern branch of the MCI Intern ...
, thrived for fifteen more years, and its west-coast counterpart MAE-West continued for more than twenty years. Today, the phrase "Network Access Point" is of historical interest only, since the four transitional NAPs disappeared long ago, replaced by hundreds of modern Internet Exchange Points, though in Spanish-speaking
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Latin America
, the phrase lives on to a small degree, among those who conflate the NAPs with IXPs.


Function

The primary purpose of an IXP is to allow networks to interconnect directly, via the exchange, rather than going through one or more third-party networks. The primary advantages of direct interconnection are cost,
latency Latency or latent may refer to: Science and technology * Latent heat, energy released or absorbed, by a body or a thermodynamic system, during a constant-temperature process * Latent variable, a variable that is not directly observed but inferred i ...
, and
bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...
. Traffic passing through an exchange is typically not billed by any party, whereas traffic to an ISP's
upstream Upstream may refer to: * Upstream (bioprocess) * Upstream (film), ''Upstream'' (film), a 1927 film by John Ford * Upstream (mobile marketing), a company * Upstream (networking) * Upstream (newspaper), ''Upstream'' (newspaper), a newspaper covering ...
provider is. The direct interconnection, often located in the same city as both networks, avoids the need for data to travel to other cities—and potentially on other continents—to get from one network to another, thus reducing latency. The third advantage, speed, is most noticeable in areas that have poorly developed long-distance connections. ISPs in regions with poor connections might have to pay between 10 or 100 times more for data transport than ISPs in North America, Europe, or Japan. Therefore, these ISPs typically have slower, more limited connections to the rest of the Internet. However, a connection to a local IXP may allow them to transfer data without limit, and without cost, vastly improving the bandwidth between customers of such adjacent ISPs.


Operations


Technical operations

A typical IXP consists of one or more
network switch A network switch (also called switching hub, bridging hub, and, by the IEEE The Institute of Electrical and Electronics Engineers (IEEE) is a professional association A professional association (also called a professional body, professio ...

network switch
es, to which each of the participating ISPs connect. Prior to the existence of switches, IXPs typically employed
fiber-optic inter-repeater link Classic Ethernet is a family of 10 Mbit/s Ethernet standards, which is the first generation of Ethernet standards. In 10BASE-X, the 10 represents its maximum throughput of 10 Mbit/s, BASE indicates its use of baseband transmission, and ...
(FOIRL) hubs or
Fiber Distributed Data Interface Dual-attach FDDI board for SBus Fiber Distributed Data Interface (FDDI) is a standard for data transmission in a local area network. It uses optical fiber as its standard underlying physical medium, although it was also later specified to use ...
(FDDI) rings, migrating to
Ethernet Ethernet () is a family of wired computer network A computer network is a set of s sharing resources located on or provided by . The computers use common s over to communicate with each other. These interconnections are made up of te ...

Ethernet
and FDDI switches as those became available in 1993 and 1994.
Asynchronous Transfer Mode Asynchronous Transfer Mode (ATM) is a telecommunications Telecommunication is the transmission of information by various types of technologies over wire, radio, Optical system, optical, or other Electromagnetism, electromagnetic systems. I ...
(ATM) switches were briefly used at a few IXPs in the late 1990s, accounting for approximately 4% of the market at their peak, and there was an attempt by
Stockholm Stockholm (; ) is the capital Capital most commonly refers to: * Capital letter Letter case (or just case) is the distinction between the letters that are in larger uppercase or capitals (or more formally ''majuscule'') and smalle ...

Stockholm
-based IXP NetNod to use SRP/DPT, but
Ethernet Ethernet () is a family of wired computer network A computer network is a set of s sharing resources located on or provided by . The computers use common s over to communicate with each other. These interconnections are made up of te ...

Ethernet
has prevailed, accounting for more than 95% of all existing Internet exchange switch fabrics. All Ethernet port speeds are to be found at modern IXPs, ranging from 10 Mb/second ports in use in small developing-country IXPs, to ganged 10 Gb/second ports in major centers like Seoul, New York, London, Frankfurt, Amsterdam, and Palo Alto. Ports with 100 Gb/second are available, for example, at the AMS-IX in Amsterdam and at the DE-CIX in Frankfurt.


Business operations

The principle business and governance models for IXPs include: *
Not-for-profit A nonprofit organization (NPO), also known as a non-business entity, not-for-profit organization, or nonprofit institution, is a legal entity organized and operated for a collective, public or social benefit, in contrast with an entity that o ...
association Association may refer to: *Club (organization), an association of two or more people united by a common interest or goal *Trade association, an organization founded and funded by businesses that operate in a specific industry *Voluntary association ...
(usually of the participating
ISPs An Internet service provider (ISP) is an organization that provides a myriad of services for accessing, using, or participating in the Internet The Internet (or internet) is the global system of interconnected computer networks that ...
) * Operator-neutral for-profit company (usually the operator of a
datacenter A data center (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American Eng ...
hosting the IXP) *
University A university () is an educational institution, institution of higher education, higher (or Tertiary education, tertiary) education and research which awards academic degrees in several Discipline (academia), academic disciplines. Universities typ ...

University
*
Government agency A government or state agency, sometimes an appointed commission, is a permanent or semi-permanent organization in the machinery of government The machinery of government (sometimes abbreviated as MoG) is the interconnected structures and proce ...
(often the communications ministry or regulator, at national scale, or
municipal government A municipality is usually a single administrative division Administrative division, administrative unitArticle 3(1). , country subdivision, administrative region, subnational entity, first-level subdivision, as well as many similar terms, ...
, at local scale) * Unincorporated informal association of networks (defined by an open-ended multi-party contract, without independent legal existence) The technical and business logistics of traffic exchange between ISPs is governed by bilateral or multilateral
peering In computer networking A computer network is a set of computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. Modern computers can perform generic sets of oper ...
agreements. Under such agreements, traffic is exchanged without compensation. When an IXP incurs operating costs, they are typically shared among all of its participants. At the more expensive exchanges, participants pay a monthly or annual fee, usually determined by the speed of the port or ports which they are using. Fees based on the volume of traffic are less common because they provide a counterincentive to the growth of the exchange. Some exchanges charge a setup fee to offset the costs of the switch port and any media adaptors (
gigabit interface converter A gigabit interface converter (GBIC) is a standard for transceiver In radio communication, a transceiver is an electronic device which is a combination of a radio transmitter, ''trans''mitter and a Radio receiver, re''ceiver'', hence the name ...
s,
small form-factor pluggable transceiver The small form-factor pluggable (SFP) is a compact, hot-pluggable network interface module used for both telecommunication Telecommunication is the transmission of information by various types of technologies over wire A wire is a ...
s,
XFP transceiver Image:Intel_XFP.jpg, upright=1.5 , Intel XFP Transceiver (MultiMode Fiber Optics) The XFP (10 gigabit small form-factor pluggable) is a standard for transceivers for high-speed computer network and telecommunication links that use optical fiber. ...
s,
XENPAK XENPAK is a multi-source agreement, multisource agreement (MSA), instigated by Agilent Technologies and Agere Systems, that defines a fiber-optic or wired transceiver module which conforms to the 10 Gigabit Ethernet (10GbE) standard of the Institute ...
s, etc.) that the new participant requires.


Traffic exchange

Internet traffic exchange between two participants on an IXP is facilitated by
Border Gateway Protocol Border Gateway Protocol (BGP) is a standardized exterior gateway protocol The Exterior Gateway Protocol (EGP) was a routing protocol A routing protocol specifies how routers communicate with each other to distribute information that enables ...
(BGP) routing configurations between them. They choose to announce routes via the peering relationship – either routes to their own addresses or routes to addresses of other ISPs that they connect to, possibly via other mechanisms. The other party to the peering can then apply
route filtering In the context of network routing, route filtering is the process by which certain routes are not considered for inclusion in the local route database, or not advertised to one's neighbours. Route filtering is particularly important for the Border ...
, where it chooses to accept those routes, and route traffic accordingly, or to ignore those routes, and use other routes to reach those addresses. In many cases, an ISP will have both a direct link to another ISP and accept a route (normally ignored) to the other ISP through the IXP; if the direct link fails, traffic will then start flowing over the IXP. In this way, the IXP acts as a backup link. When these conditions are met, and a contractual structure exists to create a market to purchase network services, the IXP is sometimes called a "transit exchange". The Vancouver Transit Exchange, for example, is described as a "shopping mall" of service providers at one central location, making it easy to switch providers, "as simple as getting a
VLAN A virtual LAN (VLAN) is any broadcast domain that is network segmentation, partitioned and isolated in a computer network at the data link layer (OSI model#Layer 2: Data Link Layer, OSI layer 2).IEEE 802.1Q-2011, ''1.4 VLAN aims and benefits'' '' ...
to a new provider". The VTE is run by BCNET, a public entity. Advocates of green broadband schemes and more competitive telecommunications services often advocate aggressive expansion of transit exchanges into every municipal area network so that competing service providers can place such equipment as
video on demand Video on demand (VOD) is a media distribution system that allows users to access videos without a traditional video playback device and the constraints of a typical static broadcasting schedule. In the 20th century, broadcasting in the form of ...
hosts and
PSTN The public switched telephone network (PSTN) provides infrastructure Infrastructure is the set of fundamental facilities and systems that support the sustainable functionality of households and firms. Serving a country, city, or other area, i ...
switches to serve existing phone equipment, without being answerable to any monopoly incumbent. Since the dissolution of the Internet backbone and transition to the IXP system in 1992, the measurement of Internet traffic exchanged at IXPs has been the primary source of data about Internet bandwidth production: how it grows over time and where it is produced. Standardized measures of bandwidth production have been in place since 1996 and have been refined over time.


See also

* Historical IXPs **
MAE-East MAE-East was an Internet Exchange Point spread across the east coast of the United States, with locations in Vienna, Virginia; Reston, Virginia; Ashburn, Virginia; New York, New York; and Miami, Florida. It was the eastern branch of the MCI Intern ...
and MAE-West **
Commercial Internet eXchange The Commercial Internet eXchange (CIX) was an early interexchange point that allowed the free exchange of TCP/IP The Internet protocol suite, commonly known as TCP/IP, is the set of communications protocol A communication protocol is a sys ...
(CIX) **
Federal Internet Exchange Federal Internet Exchange (FIX) points were policy-based network peering points where U.S. federal agency networks, such as the National Science Foundation Network (NSFNET), NASA Science Network (NSN), Energy Sciences Network (ESnet), and MILNET wer ...
(FIX) * Associations of Internet exchange point operators: ** Euro-IX, the European Internet Exchange Association ** APIX, the Asia Pacific Internet Exchange Association ** LAC-IX, the Latin America & Caribbean Internet Exchange Association ** Af-IX, the African IXP Association * Route server *
Internet service provider An Internet service provider (ISP) is an organization that provides a myriad of services for accessing, using, or participating in the Internet The Internet (or internet) is the global system of interconnected computer networks that ...
*
Data center A data center (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American Eng ...
*
Packet Clearing House Packet Clearing House (PCH) is the international nonprofit organization responsible for providing operational support and security to critical internet infrastructure, including Internet_exchange_point, Internet exchange points and the core of ...
*
List of Internet exchange points This is a list of Internet exchange points ( IXPs). There are several sources for IXP locations, including Packet Clearing House, who have maintained the earliest list of IXPs, Telegeography, PeeringDB and the Network Startup Resource Center. Add ...


References

{{Reflist


External links


European Internet Exchange Association

Internet Exchange Directory
maintained by
Packet Clearing House Packet Clearing House (PCH) is the international nonprofit organization responsible for providing operational support and security to critical internet infrastructure, including Internet_exchange_point, Internet exchange points and the core of ...

Internet Exchange Points
from Data Center Map
PeeringDB

Lookin'Glass.Org
BGP Looking Glass services at IX's. Internet exchange points Routing